SN 1979C was a supernova about 50 million light-years away in Messier 100, a spiral galaxy in the constellationComa Berenices. The Type II supernova was discovered April 19, 1979 by Gus Johnson, a school teacher and amateur astronomer.[2] This type of supernova is known as a core collapse and is the result of the internal collapse and violent explosion of a large star. A star must have at least 9 times the mass of the Sun in order to undergo this type of collapse.[3] The star that resulted in this supernova was estimated to be in the range of 20 solar masses.[1]

The researchers observed a steady source of X-rays and determined that it was likely that this was material being fed into the object either from the supernova or a binary companion. However, an alternative explanation would be that the X-ray emissions could be from the pulsar wind nebula from a rapidly spinning pulsar, similar to the one in the center of the Crab Nebula.[4] These two ideas account for several types of known X-ray sources. In the case of black holes the material that falls into the black hole emits the X-rays and not the black hole itself. Gas is heated by the fall into the strong gravitational field.